Are there any laws about carrying a gas can on your bike? And if so, is it the same in all states?

In the state of Maryland there are no laws prohibiting carrying gas can. if you are considering carrying extra fuel for long distance riding, then I would recommend MSR camping Fuel can. This can is strong and won't leak, also should only be filled 7/8 full. Cost around 10 bucks in your local camping store or department. But a regular gas canister, I wouldn't recommend that for long distance, maybe in emergency situation only. Personally I carry a self priming siphon tube in my saddle bag and yet to use it.

I carry an extra large MSR type fuel can in my pack. I ran out of gas 6 times last year and once this year so far. Damn 3.5 gl tanks!!!

All states have there own laws about gas cans.  I believe most of them have to do with when the gas can was manufactured rather than how it's used.

This site has a link where all the state laws listed... http://www.pfcma.com/    Lots of legal stuff there but I think you should be fine.

Also, there is a couple of disposable, one-time use gas cans on the market.  These are banned from sale in a handful of states due to safety concerns, so keep that in mind.  They are prohibited because of concerns about disposal after they're used.

I carry a plastic one quart container desinged for atv's, I carry it in my day bag on all long trips. Usually do not run out if I fuel every 100 miles.

All states have laws, so what, ya gotta do whaty is right for you in your situation.
fuel cantainer laws
Right to carry laws
parking laws
speed laws
this that and the other laws
most laws are for the dipshits that need to be told what they can and cannot do.

need laws?  ride with someone else

I say, do what is right for you!
Hell, these are motorcycles, not 8500 lb pickup trucks.

any law we deem necessary to alter, only changes the course in life we take.

Have an awesome day

Gotta stop for a cold one WAAAAYYYYYYYYY before I run out of gas. Bar=civilization=gas.

Gieco roadside assistance plan + Cell phone + 20,000 verizon guys following me........LOL.

Actually on my long distance rides this summer I am pre planning routes and using map and GPS programs to plot in fuel locations approximately 120 - 135 miles since I can go about 150-160 on a tank. I have not yet run out however I once put 4.2 gallons in a tank that is susposed to hold 4.1 gallons so I was pretty close to walking.